Note 5 - Deposits (Details Textual) - USD ($) $ in Millions	Sep. 30, 2026	Dec. 31, 2025
Time Deposits, at or Above FDIC Insurance Limit	$ 179.6	$ 164.2
Deposits, Public Fund	127.7	113.6
Letters of Credit Outstanding, Amount	72.0	72.0
Deposits, Funds Held by Federally Recognized Tribes	28.6	31.3
Asset Pledged as Collateral [Member] \| Funds Held by Federally Recognized Tribes [Member]
Debt Securities	30.3	40.7
Federal Home Loan Bank of Des Moines [Member]
Letters of Credit Outstanding, Amount	$ 72.0	$ 72.0

Amount, after allowance for credit loss, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), investment in debt security measured at amortized cost (held-to-maturity), and investment in debt security measured at fair value with change in fair value recognized in net income (trading).

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+ Details